Foundations of Amateur Radio

Planning for an outing

Recently I had the opportunity to use a new radio whilst I was far away from my shack. It wasn't unexpected, I took the radio with me, planned for the experience and packed light with intent.

My original packing included a 10m length of coax, my analyser, some antenna weights, wire, rope, power leads, BNC adaptors, barrel connectors and a balun. Total weight came in at about 7kg. More than double the weight of the radio itself. The biggest weight came with the coax, so that stayed home. Got rid of all the "what-if" adaptors, dumped the antenna weights, dumped the balun and the analyser, added an un-un, and a multimeter and came in at just under 5kg.

The idea was to operate from the car, chuck a long-wire into a tree and make noise.

Then I got to where I was going and learnt that there were lots of SOTA peaks nearby. If you're not familiar with SOTA, it stands for Summits On The Air and it's a way of encouraging people to go out and make noise while also encouraging others to listen out for your activation of a nearby peak. As an aside, it's separate but closely related to WWFF, World Wide Flora and Fauna, since peaks are often in National Parks and who wouldn't want an excuse to activate two things in one sitting?

One of the most basic rules of SOTA is that all equipment must be operated from a portable power source (batteries, solar cells, etc). Operation is expressly forbidden using permanently installed power sources or fossil-fuel generators of any kind.

That of course means that using the battery in a car is not allowed, though I suppose I could unbolt the battery from the engine bay, but I'm pretty sure that the hire-car company would frown on that plan.

I set about attempting to find out how much power the radio actually draws at 5 Watt, and how much battery I'd need to activate a peak.

Given that my shack wasn't where I was, I couldn't just plug it into my fancy power supply and read the power draw from the display, should have done that before I left. Shoulda, Coulda, Woulda. I resorted to asking the community, but that was dependent on the kindness of strangers.

Another hitch was the battery. I came up with the brilliant plan to use one of those high-capacity jump start boxes, 18Ah or so. Picked the one I liked the best, figured out if I could ship it back to my shack on return, since it likely couldn't fly, both from a weight and a dangerous goods perspective and found a supplier locally - well 108km away - and then, me being me, I downloaded the user manual, and learnt that what I wanted to do, power my radio, was expressly, strongly, not recommended, fear of explosion and the like.

Planning foiled.

I still wanted to operate, contest to be attempted, SOTA be damned. How could I operate and not fear that I'd be draining the car battery?

A cigarette lighter mounted Volt meter!

So, now I can connect the radio directly to the battery in the car and check the voltage whilst I'm operating.

Now all I need is a parking spot with a nearby tree or gazebo and no noisy neighbours or overhead power lines.

I'll let you know how I go.

I'm Onno VK6FLAB